Global Choreographies Research Articles

Towards refinable choreographies

We investigate refinement in the context of choreographies. We introduce refinable global choreographies allowing for the underspecification of protocols, whose interactions can be refined into actual protocols. Arbitrary refinements may spoil well-formedness, which are sufficient conditions that guarantee a protocol to be implementable. We introduce a typing discipline that enforces well-formedness of typed choreographies. Then we unveil the relation among refinable choreographies and their admissible refinements in terms of an axiom scheme.

Towards Refinable Choreographies

We investigate refinement in the context of choreographies. We introduce refinable global choreographies allowing for the underspecification of protocols, whose interactions can be refined into actual protocols. Arbitrary refinements may spoil well-formedness, that is the sufficient conditions that guarantee a protocol to be implementable. We introduce a typing discipline that enforces well-formedness of typed choreographies. Then we unveil the relation among refinable choregraphies and their admissible refinements in terms of an axiom scheme.

From global choreographies to verifiable efficient distributed implementations

We define a method to automatically synthesize efficient distributed implementations from high-level global choreographies. A global choreography describes the execution and communication logic between a set of provided processes which are described by their interfaces. At the choreography level, the operations include multiparty communications, choice, loop, and branching. A choreography is master triggered: it has one master to trigger its execution. This allows us to automatically generate conflict-free distributed implementations without controllers. The behavior of the synthesized implementations follows the behavior of choreographies. In addition, the absence of controllers ensures the efficiency of the implementation and reduces the communication needed at runtime. Moreover, we define a translation of the distributed implementations to equivalent Promela versions. The translation allows verifying the distributed system against behavioral properties. We implemented a Java prototype to validate the approach and applied it to automatically synthesize micro-service architectures. We also illustrate our method on the automatic synthesis of a verified distributed buying system.

Interface Automata for Choreographies

Choreographic approaches to message-passing applications can be regarded as an instance of the model-driven development principles. Choreographies specify interactions among distributed participants coordinating among themselves with message-passing at two levels of abstractions. A global view of the application is specified with a model that abstracts away from asynchrony while a local view of the application specifies the communication pattern of each participant. Noteworthy, the latter view can typically be algorithmically obtained by projection of the global view. A crucial element of this approach is to verify the so-called well-formed conditions on global views so that its projections realise a sound communication protocol. We introduce a novel local model, group interface automata, to represent the local view of choreographies and propose a new method to verify the well-formedness of global choreographies. We rely on a recently proposed semantics of global views formalised in terms of pomsets.

Extending UN/CEFACT’s modeling methodology by a UML profile for local choreographies

UN/CEFACT’s modeling methodology (UMM) is a UML profile for specifying global choreographies of inter-organizational e-business systems. As we outline in this paper, the practical use of UMM is limited to bi-lateral business collaborations, since it does not support nested business transactions. This means UMM does not support multi-party business collaborations. UN/CEFACT argues that UMM serves as model capturing the agreements and commitments between business partners. These agreements and commitments are always on a bi-lateral basis. However, a business partner in the middle of a supply chain must establish multiple agreements and commitments with multiple partners. It is the local choreography of a business partner that binds the various bi-lateral models leading to a multi-party choreography. Unfortunately, UN/CEFACT does not give any guidance on how to model the local choreographies. We close this gap by extending UMM by a UML profile for local choreographies.